Sep 12 2006
Toray Industries, Inc. today announced that the company has successfully developed an innovative optical polyethylene terephthalate (PET) film for liquid crystal display (LCD) backlight, combining multiple optical functions. Toray’s new development integrates functions of multiple films including that of a diffuser that diffuses the light from backlight over the entire display as well as light-collimating beads sheet and prism sheet into one film. Toray plans to commercialize the newly developed film starting from the end of the current fiscal year as an advanced film material that contributes to efficient product designing by reducing the weight and the number of parts of LCDs, mainly for backlights in large-sized LCD televisions. The company also intends to expand the material’s application to various functional films and screen materials for applications including rear-projection screens by exploiting its thinness, light weight and high optical transparency as well as its superior light diffusion and collimating properties.
Development of this new function-integrating film was enabled by Toray’s proprietary film design and surface processing technologies. The key technological points of the development are as follows:
1. Realizing “high-performance internal diffusion film substrate”
The new film employs a uniquely designed “refractive index controlling polymer particle” as an element to diffuse the light of backlight over the display. Furthermore, Toray succeeded in combining high optical transparency and high light diffusion property, two disparate functions, by achieving optimal deployment of the polymer particles using a newly developed special kneading technology and high precision film forming technology. This technology is based on Toray’s innovative optical design theory and it also facilitates control of optical diffusion.
2. Controlling light rays through “special imprint”
Development of a “surface imprint technology” that makes patterns on a film surface led to Toray’s success in forming a special stripe lens layer with both light diffusion and collimating functions on the surface of an internal diffusion film substrate possessing both high optical transparency and superior light diffusion. The thickness of the lens layer is only 10 to 50 microns and light rays can be controlled according to the quality and characteristics of the backlight with the company’s unique optical design technology.
PET film is widely used as the substrate for LCDs because of its advantages such as transparency, surface smoothness, strength, heat resistance and low cost. In the area of LCD development, companies are currently pursuing components that are highly functional, small and light-weight with low production cost. Likewise, manufacturers are being urged to come up with new thin and light-weight materials for films for LCD application in order to achieve uniformity of the display by dispersing the light from fluorescent tubes and LEDs more brightly and efficiently. Mere modification of existing materials alone is no longer sufficient to meet the technological requirements of the LCD field, which are expected to get further sophisticated in the future. At the same time, integrating the light diffusion and condensation functions into a PET film has been considered impossible until now. This assumption was based on the fact that adding diffusion elements of foreign materials such as inorganic and organic particles would result in gaps between the diffusion elements and base film in the pulling process of film forming, leading to loss of optical transparency in the film, a drastic reduction in luminance and difficulties in controlling the light beam. The function-integrating film developed by Toray this time solves all these technical issues at once.